The present invention relates to a new secondary explosive and to new pyrotechnic compositions, especially new gunpowder and propellant compositions.
Secondary explosives and pyrotechnic compositions such as explosive compositions, powders for firearms, and propellants, are very widely employed both in the arms industry and in nonmilitary fields such as space technology, mining and quarrying, public works, and the like.
Very many secondary explosives and explosive compositions are known. According to J. Quinchon's "Les poudres, propergols et explosifs", volume 1: "les explosifs, Technique et Documentation" (Powders, propellants and explosives, volume 1: explosives, Technology and Data), 1982, there may be mentioned, for example:
as secondary explosives: trinitrotoluene (tolite or TNT), trinitrophenol, trinitrotriaminobenzene (TATB), hexanitrostilbene (HNS), pentrite, nitroglycerine, hexogen (RDX), octogen (HMX), tetryl, nitroguanidine (NGu), dinitroglycolurea and tetranitroglycolurea, PA1 as explosive compositions: industrial explosives such as, in particular dynamite and nitrate explosives, and military explosive compositions such as, in particular wax-explosive mixtures (hexowaxes, octowaxes, and the like), tolite-based mixtures (hexolites, pentolites, and the like) and mixtures containing a plastic binder, among which a distinction may be made between those manufactured by compression (compressed explosives) and those manufactured by casting (compound explosives). PA1 density (.rho.): 1.91 g/cm.sup.3 PA1 detonation velocity: 7,770 m/s at .rho.=1.71 g/cm.sup.3 PA1 impact sensitivity: 22 J PA1 friction sensitivity: 7% at 353 N.
It is also known to use secondary explosives, for example HMX, RDX, NGu, as an oxidizer charge in powders for firearms, or in propellants.
In particular, there may be mentioned, without implying any limitation:
triple-base powders for firearms, consisting of nitrocellulose-nitroglycerine, nitroguanidine or hexogen,
compound powders with an inert binder for firearms, which essentially comprise an organic binder (for example polyurethane) and a secondary explosive which acts as an oxidizer charge (for example hexogen), and
compound propellants filled, for example, with octogen or ammonium nitrate (in the case of gas-generating propellants).
In the technology of explosives it is well-known that for some applications it is necessary to use secondary explosives which combine a high density with a high detonation velocity.
Secondary explosives which meet both these conditions and which are used to this day are, chiefly: cyclotetramethylenetetranitramine, also known as octogen or HMX, and cyclotrimethylenetrinitramine, also known as hexogen or RDX.
The explosive characteristics of these products are known; the main ones are collated- in Table 1, in comparison with those of tolite.
TABLE 1 ______________________________________ OCTOGEN HEXOGEN TOLITE ______________________________________ Density .rho. (g/cm.sup.3) 1.91 1.82 1.65 Detonation velocity 9,100 at 8,850 at 6,960 at (m/s) .rho. = 1.91 .rho. = 1.82 .rho. = 1.65 -8,520 at -.rho. 1.71 Impact sensitiv- 5.2 4.5 (CH) 48% at ity (J) 5.5 (B) 50 J Friction sensitiv- 100 113 (CH) 290 ity (N) 174 (B) ______________________________________
Since the detonation velocity varies with the density, the results include the corresponding density.
The sensitivity of the explosives depends, among other factors, on the commercial variety. In the case of hexogen, the results are given for two of these (B and CH).
Impact sensitivity and friction sensitivity are determined by means of the Julius Peters apparatus, according to the method described by H. D. Mallory (The development of impact sensitivity tests at the Explosive Research Laboratory, Bruceton, Pa. during the years 1941-1945 US Naval Ordnance Lab.; White Oak, Md., 1956, report 4236).
When the maximum energy of the test apparatus is reached, the percentage of detonations in tests at this energy is shown.
Compared to tolite, octogen and hexogen have the major advantage of having markedly higher densities and detonation velocities. The disadvantage of these compounds, however, is that they are very markedly more sensitive to impact and to friction than tolite, and this results in some difficulties or constraints in use.
The use of secondary explosives in munition charges requires them to be provided in the form of suitable compositions. It is becoming increasingly rare for a secondary base explosive to be used directly; it is formulated in a variety of explosive compositions which are more appropriate to the constraints in their use and to its operational requirements.
Bearing in mind the sensitivity of certain compositions, it has been necessary to develop desensitized explosive compositions in order to enable these compositions to be charged and handled more easily.
For this purpose, for example, a binder which is either plastic and inert, or active such as molten tolite, has been incorporated in the compositions. Nevertheless, when subjected to some attacks such as, for example, bullet impact, these compositions are still too sensitive, and this has led to a search for solutions in terms of the secondary explosive itself, in addition to coating with a less sensitive binder.
For this purpose it is known, for example, to use TATB as a partial replacement for HMX or RDX in explosive compositions.
TATB and tolite exhibit low sensitivity to external attacks (impact, friction, temperature rise), and this enables the sensitivity of compositions to be reduced, at the cost, however, of a drop in performance.
It has now found that, unexpectedly, 5-oxo-3-nitro-1,2,4-triazole (generally referred to as oxynitrotriazole) has advantageous properties which enable it to be used as a secondary explosive instead of, and as a replacement for, octogen or hexogen, while exhibiting a sensitivity which is as low as that of tolite.
These advantageous properties are the following:
The calculated detonation velocity at .rho.=1.91 g/cm.sup.3 is 8,590 m/s.
The methods employed are the same as those employed to obtain the results shown in Table 1.
Oxynitrotriazole has the enormous advantage of having an explosive performance which lies close to that of hexogen, bearing in mind its high density, without having the sensitivity of hexogen or octogen (refer to Table 1).
Partial or total substitution of oxynitrotriazole for hexogen enables the sensitivity of explosive compositions to be reduced while retaining virtually the same performance level. Partial substitution of oxynitrotriazole for octogen enables, while retaining a satisfactory performance level, the sensitivity of the explosive compositions to be reduced so as to meet a users' requirement which could not be met by a charge containing octogen alone.
These unexpected results permit a considerable technological step forward in the field of explosive compositions.
It has also been found that oxynitrotriazole could be used as an oxidizer charge instead of, and to replace, explosive substances which are usually employed in powders for firearms, such as, for example, triple-base powders and compound powders, as well as in compound propellants.
When compared to the use of powders which are known at present, the use of oxynitrotriazole in powders for firearms produces, unexpectedly, a lowering in the flame temperature, and consequently a decrease in erosion of the firearm barrel, and this is of great importance in practice.
Furthermore, the use of oxynitrotriazole as a replacement for ammonium nitrate in gas-generating compound propellants offers a number of advantages, the greatest of which is that oxynitrotriazole is markedly less hygroscopic than ammonium nitrate.